Brake mechanism for magnetic tape reel mounts in a video tape recorder

ABSTRACT

A brake mechanism for magnetic tape reel mounts in a video tape recorder in which a tape is pulled out and stowed by stopping a take-up reel mount while rotating a supply reel mount at the time of loading and unloading. The mechanism is provided with an idler wheel capable of engaging with idler engagements of each of the reel mounts and a pair of brakes capable of simultaneously engaging with brake engagements of both reel mounts. The idler engagement of the supply reel and the brake engagement of the supply reel are connected means of a one way clutch. At the time of unloading, the pair of brakes are engaged with the brake engagements of both reel mounts while the idler wheel is engaged with the idler engagement of the supply reel mount to rotate only the supply reel mount.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to magnetic tape reel mounts in a videotape recorder, hereinafter referred to as a "VTR", and moreparticularly, to a brake mechanism for reel mounts in a VTR in which atape is pulled out and stored by stopping a take-up reel mount and byrotating a supply reel mount at the time of loading and unloading.

2. Description of the Prior Art

A conventional tape-loading mechanism for a VTR is disclosed in U.S.Pat. Nos. 4,115,825 and 4,426,668. In this type of mechanism for a VTR,it is desirable that the tape position be the same when the tape isreloaded for playing and recording as the position of the tape when itwas previously unloaded. The reason for this is to make the last picturein the first playing operation and the initial picture in the secondplaying operation continuous and also to maintain the indication of atape counter consistent.

Conventionally, to accomplish these purposes, only one of the supply andtake-up reel mounts is braked and the other is rotated, whereby loadingand unloading of the magnetic tape are accomplished.

Also, in the conventional VTR, the brakes are applied to both of thereel mounts at the time of stopping so as to prevent the tape fromslackening, and are relased at the time of playing.

Conventional brake mechanisms have required the use of two brakesystems, and this has caused complication of the mechanism.

SUMMARY OF THE INVENTION

The present invention was developed taking the above-mentioned problemsinto consideration. The object of the present invention is to provide asingle brake mechanism which operates on both the supply and the take-upreel mounts simultaneously, which is of simple construction and whichincludes a one-way clutch by which the tape position doesn't changenotwithstanding repeated loadings and unloadings. The object of thepresent invention is also to provide a brake mechanism for magnetic tapereel mounts of simple construction in which an idler wheel is broughtinto engagement with the reel mounts in a wedged fashion in the rotarydirection of the reel mounts, whereby the reel mounts can be braked bythe wedging action of the idler wheel.

The present invention provides a brake mechanism for magnetic tape reelmounts in a VTR of the type that receives magnetic tape stored on tworeels rotatably mounted internally of a cassette which includes a tapesupply reel mount and a take-up reel mount, each of the reel mountsincluding an idler engagement and a brake engagement portion, an idlerwheel mounted for movement into engagement with either of the idlerengagement portions of the tape reel mounts, means driving the idlerwheel for selective rotation in opposite directions and a pair of brakemeans for simultaneously engaging and disengaging with the brakeengagement portions of the tape reel mounts. A one-way clutch isprovided to connect the idler engaging portion and the brake engagingportion of the tape supply reel mount and is operative to drivinglyengage the idler engagement portion and the brake engagement portiononly when the idler engagement portion rotates in one direction andpermits the idler engagement portion of the tape supply reel mount torotate independently of the brake engagement portion when the idlerengagement portion rotates opposite to that one direction. Loading meansare provided in the VTR for pulling the magnetic tape out of thecassette and disposing the tape in contact with a guide cylinder. At thetime of unloading, the pair of brake means are actuated to engage thebrake engagement portions of the supply and take-up reel mounts and theidler wheel engages the idler engagement portion of the tape supply reelmount and rotates that idler engagement portion to withdraw the magnetictape from the guide cylinder by rewinding the magnetic tape on the tapesupply reel mount.

Moreover, the brake mechanism of the present invention also includesmeans for wedging the idler wheel with the idler engagement of the tapetake-up reel mount at the time of loading the magnetic tape in the VTRwhich permits the pair of brake means to be disengaged from the brakeengagement portions of both tape reel mounts thereby permitting the tapesupply reel mount to rotate freely and unwind tape as required by theloading means pulling tape out of the cassette.

The invention and the advantages provided thereby will be more fullyunderstood with reference to the following detailed description of thepreferred embodiment taken in conjunction with the accompany drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Hereinafter the present invention will be described in detail withreference to the accompanying drawings wherein:

FIG. 1 is a plan view of a VTR tape loading mechanism in which thepresent invention is schematically shown;

FIG. 2 is a plan view in which the brake mechanism of FIG. 1 isschematically shown;

FIG. 3 is an elevational view, partly in section, showing a tape supplyreel mount of FIG. 2;

FIG. 4 is a transverse sectional view taken along the line IV--IV ofFIG. 3;

FIG. 5 is an elevational view, partly in section, showing a tape take-upreel mount of FIG. 2; and

FIGS. 6(A-E) are plan views schematically illustrating the operation ofthe brake mechanism shown in FIG. 2 at the time of stopping, loading,playing, reverse reproducing and unloading the tape.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to the drawings wherein the same reference numeralsidentify the same members throughout, FIG. 1 shows a tape-loadingmechanism in a VTR, in which a tape supply reel mount 2, a tape take-upreel mount 3 and a guide cylinder 4 are mounted on a chassis 1. An idlerwheel 5 is arranged between the tape reel mounts 2 and 3 and tape guides8 and 9 are placed in each of a pair of guide grooves 6 and 7respectively.

A tape cassette 10 is set on the chassis 1, with a supply reel 12 and atake-up reel 13 for a tape 11 fitting on the supply reel mount 2 and thetake-up reel mount 3 respectively. When the tape 11 in the tape cassette10 is pulled out of the cassette 10 by the tape guides 8 and 9, andwound onto the guide cylinder 4 and the take-up reel mount 3 is drivenby the idler wheel 5, the tape 11 is recorded or reproduced. This typeof loading and playing of the tape 11 is the same as that utilized in aconventional VTR.

The idler wheel 5 disposed between the supply reel mount 2 and thetake-up reel mount 3 is driven by a drive pulley 15 to rotateselectively in a forward direction or the opposite direction and isswung so as to engage an idler engagement 2a of the supply reel mount 2or an idler engagement 3a of the take-up reel mount 3. That is, theidler wheel 5, being supported by a support level 16 attached rotatablyto a shaft of the drive pulley, is adapted to be able to be swungtogether with the support lever 16 around the shaft, while being pressedonto the drive pulley 15 all the time by a spring 17, so that the idlerwheel 5 is rotated by the drive pulley 15. When the drive pulley 15 isdriven in the forward direction, the idler wheel 5 is swung toward theidler engagement 3a of the take-up reel mount 3 and contacts the idlerengagement 3a to rotate the take-up reel mount 3 clockwise as shown inthe drawing. On the other hand, when the drive pulley 15 is rotated inthe opposite direction, the idler wheel 5 is swung toward the idlerengagement 2a of the supply reel mount 2 and contacts the idlerengagement 2a, whereby the supply reel mount 2 is rotatedcounterclockwise in the drawing.

The direction the drive pulley 15 is driven is changed and controlled bya regular motor for forward and reverse rotation and a connection andchange-over switch thereof (not shown). The driving force for rotatingthe drive pulley 15 can also be changed by switching over the voltageapplied to the regular motor and thereby providing forward and reverserotation.

Consequently, the idler wheel 5, as shown in FIG. 6(B), is engaged withthe idler engagement 3a of the take-up reel mount 3 by a weak forwardrotary force of the drive pulley at the time the tape 11 is loaded.

At the time of playing, as shown by FIG. 6(C), the idler wheel 5 isengaged with the idler engagement 3a of the take-up reel mount 3 by astrong forward rotary force of the drive pulley, whereby the take-upreel mount 3 is driven to rotate. At the time of unloading of the tape1, as shown by FIG. 6(E) and of reverse reproducing, FIG. 6(D), theidler wheel 5 is engaged with the idler engagement 2a of the supply reelmount 2 by the counter or opposite rotation of the drive pulley, wherebythe supply reel mount 2 is driven to rotate. The idler wheel 5 isreleased at the time of stopping as shown by FIG. 6(A).

The supply reel mount 2 and the take-up reel mount 3 include idlerengagements 2a and 3a and brake engagements 2b and 3b respectively aswill be described hereafter with reference to FIGS. 3 through 5.

Referring now to FIG. 2 where the reel mount mechanism is shown, brakeshoes 18 and 19 are disposed facing the brake engagement 2b of thesupply reel mount 2 and the brake engagement 3b of the take-up reelmount 3 respectively. Brake levers 20 and 21 with brake shoes 18 and 19fitted thereto respectively are pivoted onto the chassis 1 by supportingshafts 22 and 23 respectively. The brake levers are also attached tocoil springs 24 and 25, so that the brake levers can be pressed onto thebrake engagements 2b and 3b through the brake shoes 18 and 19 by theforce of the coil springs 24 and 25.

A brake release lever 30 having a pair of moving parts 28 and 29 facingengagement ends 26 and 27 of the brake levers 20 and 21 respectively isattached to a plunger 31 mounted on the chassis 1. When the plunger 31is operated, the release lever 30 is moved in one direction and theengagement ends 26 and 27 of the brake levers 20 and 21 are pressed bythe moving parts 28 and 29. The brake levers 20 and 21 are thus rotatedaround the shafts 22 and 23 against the spring force of the coil springs24 and 25, whereby the pair of brake shoes 18 and 19 are released fromthe brake engagements 2b and 3b at the same time.

In other words, when the plunger 31 is out of operation, the brake shoes18 and 19 of the pair of brake levers 20 and 21 are pressed onto thecorresponding brake engagements 2b and 3b of the supply reel mount 2 andthe take-up reel mount 3 respectively by the force of the coil springs24 and 25, and the brakes are thus applied. On the other hand, when theplunger is in operation, the brake release lever 30 is put intooperation, so that the brake shoes 18 and 19 of the pair of brake levers20 and 21 will be separated from the brake engagements 2b and 3b of thecorresponding supply reel mount 2 and the take-up reel mount 3simultaneously so as to release the brakes. Consequently, the plunger 31serves to change or switch over the brake. As shown by FIGS. 6(B-D), atthe time of loading, playing and reverse reproducing of the tape 11, thebrake shoes 18 and 19 are simultaneously released by putting the plungerinto operation. At the time of stopping and unloading of the tape 11, asshown by FIGS. 6(A & E), the spring force of the coil springs 24 and 25puts the brake shoes 18 and 19 in contact with the brake engagements 2aand 2b with the plunger out of operation.

As shown in FIGS. 3 through 5, the supply reel mount 2 and the take-upreel mount 3 are rotatably provided on supporting shafts 32 and 33arranged on the chassis 1 respectively.

As shown in FIG. 3, the supply reel mount 2 comprises a hub engagement2c which a hub of the cassette supply reel (not shown) engages, an idlerengagement 2a which rotates together with the hub engagement and whichthe idler wheel 5 engages, and a brake engagement 2b which the brakeshoe 18 engages.

The idler engagement 2a and the brake engagement 2b are connected by aone-way clutch 34 as shown in FIG. 4. Thus, an annular body 2e isarranged radially outside of a cylindrical portin 2d integral with thebrake engagement 2b. A plurality of rollers 2g are arranged in camportions 2f formed at the radially inner side of the annular body 2e soas to be rotated in contact with the cylindrical portion 2d. A pluralityof projecting portions 2h are formed integral with the radially outeredge of the annular body 2e and engage the radially inner side of theidler engagement 2a, so that the annular body 2e and the idlerengagement 2a rotate together as one piece.

The one-way clutch 34 constructed as described above acts so that whenthe idler engagement 2a is rotated clockwise, the roller 2g will grip orbite between the cylindrical portion 2d and the annular body 2e, and theidler engagement 2a and the brake engagement 2b will rotate together asone piece. When the idler engagement 2a is rotated counterclockwise, theroller 2g is free to rotate and race and the coupling between the idlerengagement 2a and the brake engagement 2b is released.

On the other hand, the idler engagement 3a and the brake engagement 3bof the take-up reel mount 3 shown in FIG. 5 are formed as integral partsof the same body so as to rotate together with a hub engagement 3c,which a hub (not shown) of the cassette take-up reel engages.

The movement of a VTR tape loading mechanism having the above-describedstructure will be described with reference to the various states ofoperation as shown by FIGS. 6(A-E).

When the tape loading mechanism is stopped as shown by FIG. 6(A), thedrive pulley 15 is stopped and the plugner 31 is out of operation,enabling the brake shoes 18 and 19 to be pressed onto the brakeengagements 2b and 3b of the supply reel mount 2 and the take-up reelmount 3 respectively by the coil springs 24 and 25.

When the tape loading mechanism is stopped, the take-up reel mount 3 isprohibited from rotating by the brake shoe 19. As for the supply reel 2,the idler engagement 2a is prohibited from rotating clockwsie, since theidler engagement 2a and the brake engagement 2b (and others) areintegrally incorporated by the operation of the one-way clutch 34 asshown by FIG. 4 and the supply reel mount 2 is prohibited from rotatingclockwise.

Consequently, the tape doesn't have any slack at the time of stopping,because on one hand the take-up reel mount 3 is stopped and on the otherhand the supply reel mount 2 is prohibited from rotating clockwise.

When the playing operation is initiated after the stopping mode shown inFIG. 6(A), the drive pulley 15 starts to rotate clockwise by a weakforce, whereby the idler wheel 5 is swung clockwise and comes intocontact with the idler engagement 3a of the take-up reel mount 3.However, the force applying rotation to the drive pulley is small atthis time and there is no possibility that the take-up reel mount willbe rotated against frictional force of the brake. The plunger 31 is thenactuated to slide the brake release lever 30 to the left by the suctionof the plunger 31 and release the brake levers 20 and 21. After that,loading of the tape 11 is started, as shown in FIG. 6(B), by thesucceeding movement of a loading means consisting of tape guides 8 and9.

Now, the angle θ made between a line connecting the idler wheel 5 andthe drive pulley 15 and a line connecting the idler wheel 5 and thetake-up reel mount 3 is greater than 90° (θ>90°) as shown in FIG. 6(B),and the idler wheel 5 and the take-up reel mount 3 are located so thatthey are wedged into each other. Therefore at the time of loading, thetake-up reel mount 3 will not be rotated because the idler wheel 5serves as a brake holding the take-up reel mount 3 against rotationnotwithstanding movement of the tape guides 8 and 9 and the tape 11which would otherwise tend to rotate the take-up reel mount 3counterclockwise.

Thus, the tape 11 is pulled out of the cassette 10 and loaded byrotating only the supply reel mount 2. As the drive pulley is applied aclockwise rotation by a weak force throughout the loading, the idlerwheel 5 is continually in contact with the idler engagement 3a of thetake-up reel mount 3, whereby the idler wheel 5 serves as a brake.

With the tape 11 loaded, the take-up reel mount 3 is rotated clockwiseby the idler wheel 5 at the time of playing as shown by FIG. 6(C). Atthe time of reverse reproducing as shown by FIG. 6(D), the supply reelmount 2 is rotated counterclockwise by the idler wheel 5.

When the operation for unloading the tape 11 is initiated, the suctionof the plunger 31 is released and the brake levers 20 and 21 engage thebrake engagements 2b and 3b of the supply reel mount 2 and the take-upreel mount 3 respectively by the aid of the coil springs 24 and 25 asshown in FIG. 6(E).

Furthermore, the drive pulley 15 is driven to rotate counterclockwiseand the idler wheel 5 is brought into engagement with the idlerengagement 2a of the supply reel mount 2. Then, the idler engagement 2aand the supply reel 2 are rotated counterclockwise, since the idlerengagement 2a can be rotated counterclockwise independently of the brakeengagement 2b as permitted by operation of the one-way clutch 34 asshown in FIG. 4 even though the brake shoe 18 of the brake lever 20engages the brake engagement 2b.

Therefore, at the time of unloading, the take-up reel mount 3 is stoppedfrom rotating and the tape 11 is stowed in the cassette 10 with therotation of only the supply reel mount 2.

In the event the tape on the supply reel runs short at the beginning ofthe loading operation or during the loading operation, and abnormaltension will be added to the tape with the above-described loadingmethod. For this reason, a tape end detecting system (for example, anoptical detector) is actuated in the disclosed embodiment as soon as thetape end is detected thereby, and even at the time of loading the modeof loading is changed to the mode of unloading.

As described above in detail with reference to the preferred embodiment,according to the present invention, one of the reel mounts is stopped atthe time of loading and unloading without such brake mechanisms as areconventionally used to individually brake the supply reel mount and thetake-up reel mount, and only the other of the reel mounts can berotated, whereby deviation of a tape positon as previously caused byrepetition of loading and unloading operations can be prevented with asimple mechanism.

Consequently, the brake mechanism of the reel mounts according to thepresent invention is industrially of great utility value in that it canbe widely applied to various types of tape loading mechanisms in varioussystems of a VTR, and that it can provide a sure brake actuation andbrake release function with the simple construction disclosed herein.

What is claimed is:
 1. A brake mechanism for magnetic tape reel mountsin a video tape recorder of the type that receives magnetic tape storedon two reels rotatably mounted internally of a cassette comprising:firstand second tape reel mounts, said first and second tape reel mountsrespectively including first and second idler engagement portions andfirst and second brake engagement portions, an idler wheel mounted formovement into engagement with either of said first and second idlerengagement portions of said first and second tape reel mounts, meansdriving said idler wheel for selective rotation in opposite directions,a pair of brake means for simultaneously engaging and disengaging withsaid first and second brake engagement portions of said first and secondtape reel mounts, a one-way clutch connecting said first idler engagingportion and said first brake engaging portion of said first tape reelmount and operative to drivingly engage said first idler engagementportion and said first brake engagement portion only when said firstidler engagement portion rotates in one direction and permitting saidfirst idler engagement portion of said first reel mount to rotateindependently of said first brake engagement portion of said first reelmount when said first idler engagement portion rotates opposite to saidone direction, and loading means for pulling the magnetic tape out ofthe cassette and disposing said tape in contact with a guide cylinder,whereby, at the time of unloading, said pair of brake means engage saidfirst and second brake engagement portions of said first and second tapereel mounts while said idler wheel engages said first idler engagementportion of said first tape reel mount and rotates said first idlerengagement portion in said direction opposite to said one direction towithdraw said tape from said guide cylinder by rewinding said magnetictape on said first tape reel mount.
 2. The brake mechanism for magnetictape reel mounts as defined by claim 1 further including means forwedging said idler wheel with said second idler engagement portion ofsaid second tape reel mount and whereby at the time of loading, saidpair of brake means are disengaged from said first and second brakeengagement portions of said first and second tape reel mounts and saididler wheel is engaged with said second idler engagement portion of saidsecond tape reel mount and wedged to prevent rotation of said secondtape reel mount while said first tape reel mount is free to rotate andunwind tape as required by said loading means pulling tape out of saidcassette.